1. Field of the Invention
This invention relates to magnetic recording media, such as the recording media used in hard disk drives, and in particular to patterned recording media. Still more particularly, the present invention relates to a method and system for initializing patterned media.
2. Description of the Prior Art
Designers, manufacturers, and users of computing systems require reliable and efficient digital information storage and retrieval equipment. Conventional magnetic disk drive systems are typically used and are well known in the art. As the amount of information that is stored digitally increases, however, users of magnetic recording media need to be able to store larger and larger amounts of data. To meet this demand, designers of magnetic recording media are working to reduce the size of the features on a recording disk, because the storage capacity of a recording disk is a function of the number of closely spaced concentric tracks on the disk. Some of the recording disk surface area, however, must be used for purposes other than data storage.
Some systems use various types of indexing marks and alignment indicia to help keep the read and write head(s) properly aligned on a particular track. These marks and indicia are often recorded in servo sectors, which are angularly spaced reserved portions of the recording disk surface that extend out approximately radially from the disk centers. Track addresses and angular synchronization signals that determine the circumferential location of the magnetic head can also be recorded in servo sectors. Position error signal (PES) bursts are often recorded in servo sectors for generation of position error signals that are used to keep the read and write head(s) aligned. Servo sectors use recording disk surface area that could otherwise be used for data storage. Consequently, servo sector information must be stored as efficiently as possible in order to leave as much space as possible for data storage.
Additionally, as the demand to store more data on each disk increases, designers are increasing the number of tracks on each disk. However, with track densities at and exceeding ten thousand tracks per inch, the tasks of increasing data storage capacity and writing servo patterns with suitable geometric accuracy are becoming increasingly difficult. Therefore, developing new techniques for manufacturing and using magnetic recording media remain significant considerations for designers, manufacturers, and users of contemporary electronic devices.
In accordance with the present invention, a method and system are disclosed for initializing patterned media. The process begins by DC initializing (i.e. erasing) at least a portion of the recordable regions on the patterned media. At least one offset may then be determined. The at least one offset compensates for at least one delay. For example, the at least one offset may compensate for delays in the electronics, one example being a read to write delay. Furthermore, the at least one offset may compensate for at least one delay caused by the space separation between at least one write head and at least one read head.
In certain embodiments, the at least one offset may be determined by writing at least one test mark on at least a portion of the initialized recordable regions. Position and/or timing information is recorded when the at least one test mark is written, when the test mark is first detected by a read head, and when the test mark is last detected by the read head. This information may then be used to determine at least one offset, such as a radial and a circumferential offset.
After the at least one offset is determined, a plurality of position error signal (PES) bursts may be written on at least a portion of the initialized recordable regions. The previously written PES bursts may be used to determine PES signals for guiding the at least one write head as new PES burst fields are written. When all of the desired PES bursts have been written, a gray code may be written on at least a portion of the recordable regions. The gray code may be used to define a track number for the data tracks with no eccentricity. In certain embodiments, the gray code may be written as two sets of gray code in order to compensate for side erasure gaps in the first set of gray code.
A system for initializing pattern media may include a null mark detector, a servo timing mark (STM) and interval detector, a PES detector, and a pattern generator with a delay. The null mark detector may be used to detect transitions in a null-type PES pattern while the PES detector may be used to detect PES bursts. The servo timing mark (STM) and interval detector may be used to determine the at least one offset. The pattern generator with delay may be used to generate a data pattern for the written data, such as the gray code. The delay circuit may be used to determine when a write head is positioned over the proper location on the media before data is written to the media.
The null mark detector, servo timing mark (STM) and interval detector, PES detector, and pattern generator with delay may be configured and implemented in any desired manner. For example, in certain embodiments, the null mark detector, servo timing mark (STM) and interval detector, and PES detector may be implemented as hard wired logic within the system.